Poultry has long been grown in enclosed areas within which the birds are supplied with food and water. The close confinement of the birds sometimes leads to conditions in which disease can propagate. As a result, in recent years poultry growers have increasingly supplied preventive medication to poultry by including such medication in dissolved form in water supplied to the birds for drinking.
Poultry watering is a well-developed art. Nevertheless, with increasing use of medication and other additives in the poultry drinking water, the poultry watering valves (which are sometimes referred to as "nipples") tend to foul or clog, which causes the valves to leak unacceptably and/or become completely inoperative. Further, when the rubber sealing gaskets used in prior art poultry watering devices absorb the water/additive mixture, the sealing gaskets change shape and thereby adversely affect the performance of the watering device. In either case maintenance is required and, if a valve becomes so fouled that it will not open, one or more birds depending on that valve for water may die.
In addressing such problems the industry has developed valves, particularly ball valves, which are of all metal construction in order to minimize the risk of fouling created by the presence of medication or other additives in the poultry water. Typical of such ball valves are the valves shown in U.S. Pat. Nos. 4,491,088; 4,525,724; 4,610,221; and 4,984,537. Two patents showing valves or nipples developed specifically to address the fouling problem are U.S. Pat. Nos. 4,606,301 and 4,660,509.
While valves constructed according to the disclosures of U.S. Pat. No. 4,606,301 and 4,660,509 have experienced some acceptance in the marketplace, a continuing problem with poultry watering valves, specifically with poultry-actuated watering valves, is the relatively high force required for the bird to "toggle" or open the valve. The all metal valve constructions disclosed in the prior art require relatively high toggle forces to actuate the valve. Young birds or birds which have been debeaked may not be able to exert the high toggle force necessary to open prior art valves in order to drink.
Other United States patents known to Applicant and which may be material respecting this invention are U.S. Pat. Nos. 1,454,284; 2,710,594; 2,851,007; 3,476,088; 3,675,627; 3,756,199; 4,284,036; 4,402,343; 4,421,060; 4,589,373; 4,637,345; 4,524,724; 4,589,373; 4,606,301; 4,610,221; 4,637,345; 4,790,264 and 4,896,629.
Other United States patents which illustrate the general state of the poultry watering art, as known to Applicant, include U.S. Pat. Nos. 4,221,188; 4,543,912; 4,669,422; 4,724,797; 4,770,126; 4,793,291; 4,884,528; 5,009,194; 5,016,574; 5,105,770; 5,136,982 and 5,136,983.